Potential of integrated flight scheduling and rotation planning considering aerodynamic-, engine- and mass-related aircraft deterioration

Abstract

Aircraft are subject to steady deterioration effects in flight operations resulting in increased fuel consumption due to decreased engine efficiency, increased airframe surface roughness and increased operating empty mass. These effects are taken into account in operational flight planning (e.g. fuel calculations) but long-term efficiency loss is rarely respected in flight and rotation scheduling. In most cases, each aircraft type per fleet series is treated homogeneously and scheduled considering maintenance events, equipment and other restrictions. This work investigates fuel saving potentials by additionally considering the aircraft tail sign-specific efficiency during aircraft to flight assignment. For this purpose, we calculate additional fuel consumption caused by deterioration effects, expressed as performance factor and mass deviation. By using an integrated flight scheduling and aircraft rotation model, aircraft will be reassigned to flights from given flight schedules by minimizing operating costs or fuel consumption. Our research yields in a saving of 22,400 kg fuel for 15 long-haul aircraft (150 kg per reassigned flight on average) based on a flight schedule for a typical week of an air cargo operator. The saving potential depends on the number of flight legs, their distance and the number of available aircraft, their performance variation and loading factor. Although relative savings are of theoretical nature and marginal to total fuel burn (0.2%), we propose an inexpensive approach to decrease total fuel consumption. Furthermore, we show that the usual approach of assigning less efficient aircraft to short flight legs is applicable but does not always provide in the cost minimum solution because low cruising altitudes of short-haul flights adversely affect fuel consumption.